<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="./css/bootstrap.css">
    <title>Document</title>
</head>
<body>
    <a href="" class="btn">按钮1</a>
    <a href="" class="btn btn-default">按钮1</a>
    <button class="btn btn-default">按钮2</button>
    <input type="button" value="按钮3" class="btn btn-default">
    <!-- 其他元素也可以使用按钮样式但是功能会受影响 -->
    <div class="btn btn-default">按钮4</div>
    <hr>
    <button class="btn btn-default">默认样式</button>
    <button class="btn btn-primary">首选项</button>
    <button class="btn btn-success">成功</button>
    <button class="btn btn-info">一般信息</button>
    <button class="btn btn-warning">警告</button>
    <button class="btn btn-danger">危险</button>
    <button class="btn btn-link">连接</button>
    <hr>
    <button class="btn btn-default btn-lg">大</button>
    <button class="btn btn-default btn-sm">中</button>
    <button class="btn btn-default btn-xs">小</button>
</body>
</html>